1. Field of the Invention
The present invention relates to a wireless receiving apparatus and a method therefor, and more particularly to a technology for recording wireless transmitted image information on a recording medium.
2. Related Background Art
There is recently proposed a configuration of the video camera which is divided into a camera unit for generating image information from the optical image of the object and a recording unit for recording the image information generated by the camera unit and in which the image information of the camera unit is wireless transmitted to the recording unit.
FIG. 1 is a block diagram showing the configuration of an image pickup device 100 having the above-mentioned camera unit, and FIG. 2 is a block diagram showing the configuration of a recording device 200 having the above-mentioned recording unit.
Referring to FIG. 1, there are provided a camera unit 102 for converting the optical image of the object into an electrical signal thereby generating image signal; a control unit 104 for controlling the entire image pickup device 100, including for example focus control and exposure control; a wireless transmission circuit 106 for wireless transmission of the image signal generated in the camera unit 102 and the control signal generated in the control unit 104 to an external recording device; a wireless reception circuit 108 for demodulating the wireless signal transmitted from an external device thereby restoring the signal before transmission; an antenna 110; a switch 112 for either (a) sending the output of the wireless transmission circuit 106 to the antenna 110, or (b) sending the output of the antenna 110 to the wireless reception circuit 108 under the control of the control unit 104; and a power supply unit 114 for electric power supply to the entire image pickup device 100.
Referring to FIG. 2, there are provided an antenna 202; a switch 204 for either (a) sending the output of a wireless transmission circuit 208 to the antenna 202, or (b) sending the output of the antenna 202 to the wireless reception circuit 205; a wireless reception circuit 206 for demodulating the wireless signal transmitted from the external image pickup device thereby restoring the signal before transmission; a wireless transmission circuit 208 for effecting a modulation process for wireless transmission of the control signal, released from a control unit 212, to an external device; a recording unit 210 for recording the image information transmitted from the external device on a recording medium such as a magnetic tape and reproducing such recorded information; a control unit 212 for controlling the entire recording device 200, capable of controlling the recording and reproducing operations of the recording unit by unrepresented operation keys; and a power supply unit 214 for electric power supply to the entire recording device 200.
The above-explained configuration allows the recording device 200 to record the image information, sent by wireless transmission from the image pickup device 100, on the magnetic tape or the like by controlling the recording unit 210.
Also in recent years, the transmission of the image information by the spread spectrum communication methods is attracting attention for the wireless communication in such wireless system as mentioned above.
In the following there will be given a brief explanation of the direct sequence modulation, which is one of the modulation methods employed in the spread spectrum communication.
In the direct sequence modulation, the transmitting device effects diffusion modulation of the information signal to be transmitted (base band signal) by means of a series of diffusion codes such as pseudo noise (PN) codes, so as to obtain a signal of a band width which is extremely wider than that of the base band signal. The diffusion modulated signal, after the direct sequence modulation, is further modulated, for example by PSK (phase shift keying) or FSK (frequency shift keying), into a signal of a wireless frequency and is wireless transmitted.
The receiving device converts the received signal of the wireless frequency by a demodulation process, corresponding to the modulation process in the transmitting device, into the diffusion modulated signal. The receiving device further executes an inverse diffusion modulation on such diffusion modulated signal, utilizing a series of diffusion codes, same as that employed in the diffusion modulation of the transmitting device, thereby restoring the base band signal prior to the transmission.
In such spread spectrum communication utilizing the direct sequence modulation, the information signal is transmitted with a transmission band much wider than that of the original information signal. For this reason, if the transmission band width is given, the transfer rate is significantly lower than that in the ordinary wireless transmission without the diffused modulation. Consequently, the above-explained direct sequence modulation is not suitable for the high-speed transmission of a large amount of data such as image information.
The wireless communication system explained above has been associated with the following drawbacks. Because the image pickup device 100 and the recording device 200 are mutually separated, each device has to be equipped with a battery. Consequently, in the course of wireless communication of the image information between the image pickup device 100 and the recording device 200, in a case where the image pickup device 100 develops an abnormality (for example the transmission of the image information is disabled for example by a low battery capacity of the power supply unit 114 or by cutting off of the power supply in the image pickup device 100), the wireless reception circuit 206 and the recording unit 210 in the recording device 200 continue the process, thereby continuing the recording of the abnormal reception signal and wasting the electric power of the recording device 200.
A similar situation arises also in a case where the image information cannot be properly received for a prolonged period by a large distance between the image pickup device 100 and the recording device 200 or by the presence of an obstacle therebetween.
An object of the present invention is to solve the above-described drawbacks.
Another object of the present invention is to provide a wireless receiving device capable of controlling the recording operation in the wireless reception device according the status of reception of the signal, thereby suppressing the wasted use of the recording medium and the wasted electric power consumption.
The above-mentioned objects can be attained, according a preferred embodiment of the present invention, by a wireless receiving apparatus for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) detection means for detecting the reception status of the information signal;
b) timer means for counting time of continuation of a predetermined inferior reception status, according to the result of detection by the detection means; and
c) control means for terminating the recording operation of the recording unit in a case where the time of continuation counted by the timer means becomes at least equal to a predetermined time.
According to another embodiment, there is also provided a wireless receiving apparatus for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) detection means for detecting the reception status of the information signal; and
b) control means for controlling the recording operation of the recording unit according to the result of detection by the detection means and causing information signal, received prior to the first-mentioned information signal, to be recorded on the recording medium;
wherein the control means is adapted to terminate the recording operation of the recording unit in a case where the information signal, received prior to the first-mentioned information signal, is recorded at least for a predetermined time.
According to still another embodiment, there is also provided a wireless receiving apparatus comprising:
a) reception means for receiving a wireless transmitted image signal;
b) detection means for detecting the error status of the image signal received by the reception means;
c) recording means for recording the image signal received by the reception means; and
d) control means for controlling the recording means, according to the error status of the image signal detected by the detection means, in such a manner as to record an image signal received prior to the first-mentioned image signal;
wherein the control means is adapted to terminate the recording operation of the recording means in a case where a predetermined error status of the image signal continues at least for a predetermined time.
According to still another embodiment, there is also provided a wireless receiving apparatus comprising:
a) reception means for receiving a wireless transmitted image signal;
b) detection means for detecting the error status of the image signal received by the reception means;
c) recording means for recording the image signal, received prior to the first-mentioned image signal, according to the error status of the image signal detected by the detection means;
d) display means for displaying the image signal received by the reception means; and
e) control means for causing the display means to display a warning signal indicating the error status, in a case where a predetermined error status of the image signal continues for a predetermined time.
Still another object of the present invention is to provide a wireless receiving method capable of controlling the recording operation in the wireless reception device according the status of reception of the signal, thereby suppressing the wasted use of the recording medium and the wasted electric power consumption.
The above-mentioned object can be attained, according a preferred embodiment of the present invention, by a wireless receiving method for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) a detection step of detecting the reception status of the information signal;
b) a counting step of counting time of continuation of a predetermined inferior reception status, according to the result of detection obtained in the detection step; and
c) a control step of terminating the recording operation of the recording unit in a case where the time of continuation counted in the counting step becomes at least equal to a predetermined time.
According to another embodiment, there is also provided a wireless receiving method for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) a detection step of detecting the reception status of the information signal; and
b) a control step of controlling the recording operation of the recording unit according to the result of detection obtained in the detection step and causing an information signal, received prior to the first-mentioned information signal, to be recorded on the recording medium;
wherein the control step is adapted to terminate the recording operation of the recording unit in a case where the information signal, received prior to the first-mentioned information signal, is recorded at least for a predetermined time.
According to still another embodiment, there is also provided a wireless receiving method comprising:
a) a reception step of receiving a wireless transmitted image signal;
b) a detection step of detecting the error status of the image signal obtained in the reception step;
c) a recording step of recording the image signal obtained in the reception step; and
d) a control step of controlling the recording step, according to the error status of the image signal detected in the detection step, in such a manner as to record an image signal received prior to the first-mentioned image signal;
wherein the control step is adapted to terminate the recording operation of the recording step in a case where a predetermined error status of the image signal continues at least for a predetermined time.
According to still another embodiment, there is also provided a wireless receiving method comprising:
a) a reception step of receiving a wireless transmitted image signal;
b) a detection step of detecting the error status of the image signal obtained in the reception step;
c) a recording step of recording the image signal, received prior to the first-mentioned image signal, according to the error status of the image signal detected in the detection step;
d) a display step of displaying the image signal obtained in the reception step; and
e) a control step of displaying a warning signal indicating the error status, in a case where a predetermined error status of the image signal continues for a predetermined time.
Still other objects of the present invention, and the advantages thereof, will become fully apparent from the following detailed description of the embodiments.